Overcharging Alternator on XS650SH

[ssjody]

I admit defeat. I need your guys help figuring out my charging problem. When I rev the bike I do get more voltage but way too much. It will jump easily to 16 volts before I ever hit 3k rpms. Rev higher an it keeps climbing.

1. Here's what I know. The Stator was replaced by the PO before I ever got the bike. I have no idea what brand it is or where it came from, It's not exactly the right Stator because there's no Yellow wire that feeds the head light safety switch. When I turn the key on the Headlight comes on as soon as the key is turned on which seems strange as everything I read says that it shouldn't come on till the bike starts. I would think the Headlight wouldn't work at all since I don't have the yellow wire from the stator to feed voltage to the safety relay. This may be an entirely unrelated piece of info but maybe it's a clue.
2. Using the diagram on this site that shows how to build a regulator/rectifier, I built one using the exact same parts listed in the diagram. When I plug it in I get the same exact overcharging results. I can't rule out that the new regulator is bad but I don't have another to try.
3. To rule out my multi meter giving false readings, I installed a volt meter on my bike. I also have two multi meters and all of them show the same high voltage.
4. I can feel the three stator wires starting to get warm when I run the bike.
5. When I test the stator I get about .8 ohms of resistance on all three legs with no dead shorts on any of them
6. My brushes look fine and I'm still a couple mm's from the wear marker.
7. My Rotor bench tested good when I had it off.
8. I get about 1 volt drop at the positive brush when I turn the key on. Maybe that's expected?

Not sure what to try next.

 

[Jan_P]

Your alternator is OK Machine it is charging
Your regulator rectifier is OK since you have tried 2
But the regulator is not regulating .. I believe it is not sensing the actual charging Voltage
One needs to look at the wiring and also find out if that actual wiring is stock
Not sure if fhe below is correct

I dont know exactly how it is set up

but from the alternator there is a wire to the regulator combo
Possibly the G green

Has that connector to the Regulator / Rectifier been Inspected + ground clean and contact grease Applied so there is a solid connection ?

 

[ssjody]

Has that connector to the Regulator / Rectifier been Inspected + ground clean and contact grease Applied so there is a solid connection ?

It's a new wiring harness and the wire is Green. I have not put contact grease on it but I do have good solid continuity on both sides of the connector when I check it with my meter.

 

[Jan_P]

OK
Assuming Post 80 Regulator and Rectifier setup
What wiring is Installed Is it pre 1980 or post 1980
Any Link on internet so can Check How it looks

 

[GLJ]

Need to post what year your bike is. Also which regulator you are using and a pic of your brush rig that's on the stator.

 

[ssjody]

Any Link on internet so can Check How it looks

It’s an 81. I bought the harness off of the MikesXS. Here's a link to the one I bought. It was an exact match to the stock harness I took off. Click Here

 

[ssjody]

Need to post what year your bike is. Also which regulator you are using and a pic of your brush rig that's on the stator.

It sounds like my signature is not showing up that lists the year of my bike. Sorry about that and I'll get that fixed. Is the factory OEM reg/rectifier and stock configuration on the brush setup

 

[Jan_P]

Just to get the Basics right
The colors of wires going in to the regulator Rectifier are they the same ? on both wiring's
A quick check engine Number ..stamped low at the front and here online checking so it is not a late 80 model or so

The picture show an electronic ignition pickup
Just putting it out here On the picture the top Brush Wire white I believe is the up side 12 V and the lower the ground side
Black usually is ground Please correct if wrong.
The screws are of different length . For the brush holders I would check so it is not shorting to ground there and Bypassing Regulator Functionality all washers in place

Looks close there

 

[ssjody]

The colors of wires going in to the regulator Rectifier are they the same ? on both wiring's

Yes, I just went down and double checked to make sure. They are all the same and I get continuity on both sides of the connector

A quick check engine Number ..stamped low at the front and here online checking so it is not a late 80 model or so

I'm not sure exactly what you're asking here. It is titled as an 81, has a production date of 6/80 and the sequential number stamped on the motor matches the VIN on the bike so I believe it to be an 81

Just putting it out here On the picture the top Brush Wire white I believe is the up side 12 V and the lower the ground side

Yes, you have that correct

The screws are of different length . For the brush holders I would check so it is not shorting to ground there and Bypassing Regulator Functionality all washers in place

This may be the problem. Is there supposed to be nylon washers or screw possibly that hold the brushes in? Mine has metal screws that screw into the stator housing and would be ground the brushes out. I think that may be the problem..

 

[Jim]

Quick description of operation:
Rotor gets power from the key sw on the brown wire/brush.
Voltage regulation is by regulating the ground... green wire/brush.
What this means is the regulator provides the ground to the rotor in order to generate power.... voltage.
When the regulator senses battery voltage exceeds its "set point," it opens the ground wire, killing power passing through the rotor.
Got all that? Where I'm going is there's only two things that could cause overcharging... the regulator itself, or the green ground wire between the regulator and the brush holder. \

Since you've tried two regulators, I'd guess the green wire is shorted to ground somewhere.

 

[Jim]

The screws are of different length . For the brush holders I would check so it is not shorting to ground there and Bypassing Regulator Functionality all washers in place

I like the way you think Jan. However, the outer brush is the green/ground line back to the regulator. If that screw was too long and shorting, we'd see the outer copper ring on the rotor all chewed up... and yeah, it happens.
Looking at the pic though, the ring looks clean. Looks like, luckily that's not the case.

 

[ssjody]

Since you've tried two regulators, I'd guess the green wire is shorted to ground somewhere.

Jim, I do believe that's my problem. Is the screw that attaches the green wire supposed to be nylon? The green wire has a metal screw and I get continuity from the green brush to ground.

 

[Jan_P]

Thinking out loud --- Again I don't have this setup wondering if the brush should be turned and screwed in the upper hole ?
Measure resistance upper screw to ground ?

 

[Jim]

Jim, I do believe that's my problem. Is the screw that attaches the green wire supposed to be nylon? The green wire has a metal screw and I get continuity from the green brush to ground.View attachment 258219

You're on the right track, but no... no nylon screw.
Process of elimination... First, disconnect the regulator 'cause that's where it's supposed to ground. Take that out of the system and verify you still have that short to ground you're looking at... I'm guessing you will.
Next, remove the screw on the outer brush, hook your lead through the wire terminal and see if it's still grounded (make sure the terminal isn't touching anything on the bike). If it's still grounded, there's your problem... it should be an open line at this point. If it's still grounded, disconnect the engine main harness connector. If it's still grounded, your short in on the engine side. If it goes away, the short is in the bike harness. Now it's just a matter of looking 'till you find it.... a wire rubbed through from chaffing or some such.

 

[Jim]

Thinking out loud --- Again I don't have this setup wondering if the brush should be turned and screwed in the upper hole ?
Measure resistance upper screw to ground ?

No. Here's my run stand/test engine. The alternator works normally.

 

[ssjody]

Next, remove the screw on the outer brush, hook your lead through the wire terminal and see if it's still grounded (make sure the terminal isn't touching anything on the bike). If it's still grounded, there's your problem...

Jim & Jan_P, it was still grounded after disconnecting harness and just checking at the green brush wire loop terminal. It looks like there's where my problem lies. I'll see if I can sort that out tomorrow. Thanks for the help and Merry Christmas!

 

[Jim]

Just re-read and see you've got a new MikesXS wire harness. Has the bike done this ever since the harness was installed?

 

[Jim]

Jim & Jan_P, it was still grounded after disconnecting harness and just checking at the green brush wire loop terminal. It looks like there's where my problem lies. I'll see if I can sort that out tomorrow. Thanks for the help and Merry Christmas!

That engine harness runs behind the sprocket. That's a popular chafe point. I'd look there first.

 

[ssjody]

Just re-read and see you've got a new MikesXS wire harness. Has the bike done this ever since the harness was installed?

Yes, but before that I didn't have any charging because the wiring was all hacked up.

 

[ssjody]

That engine harness runs behind the sprocket. That's a popular chafe point. I'd look there first.

I was into that area at one point and noticed how close everything was to the sprocket. That was an area of concern but I didn't dig deep enough when I had it apart.